Re: Stalled MM patches for review

Michal Hocko
2014-12-18T16:55:07Z

On Wed 17-12-14 21:20:19, Johannes Weiner wrote:
> On Wed, Dec 17, 2014 at 02:28:37PM -0800, David Rientjes wrote:
[...]
> > Why remove 'rebalance'? In the situation where direct reclaim does free
> > memory and we're waiting on writeback (no call to the oom killer is made),
> > it doesn't seem necessary to recalculate classzone_idx.
> >
> > Additionally, we never called wait_iff_congested() before when the oom
> > killer freed memory. This is a no-op if the preferred_zone isn't waiting
> > on writeback, but seems pointless if we just freed memory by calling the
> > oom killer.
>
> Why keep all these undocumented assumptions in the code? It's really
> simple: if we retry freeing memory (LRU reclaim or OOM kills), we wait
> for congestion, kick kswapd, re-evaluate the current task state,
> regardless of which reclaim method did what or anything at all. It's
> a slowpath, so there is no reason to not keep this simple and robust.

Agreed, the less subtle loops via labels we have the better.
--
Michal Hocko
SUSE Labs